[IRCA] KGA/KPIG

["Dan Strassberg" <dan.strassberg@xxxxxxx>]

Everyone seems to assume that KGA will downgrade to a Class B to allow an
upgrade of KPIG. Although that is probably what will happen, there are
plausible scenarios under which KPIG could upgrade its night signal while
KGA remains a Class A. With the five towers at the KGA/KJRB site, KGA has
many options for modifying its night pattern to reduce radiation toward
KPIG. That reduction alone, with no change in KPIG's night pattern or power,
would improve KPIG's night coverage because KPIG's NIF contour is probably
entirely determined by the 10% skywave that KGA delivers to the north Bay
area. Remember KGA sends more than 2600 mV/m @ 1km toward KPIG. Using the
existing towers, designing an array that sends only 10% of that toward KPIG
would most likely allow KPIG to extend its NIF coverage to 10% of the
existing NIF field intensity. And KGA could probably reduce its signal
toward KPIG by a factor of more than 10 without great difficulty.

No doubt, though, KPIG wants more--that is, a substantial increase in night
power, which would allow further extension of its night coverage. As you
probably know, KPIG has a most unusual antenna system. I believe it to be
the US's only rooftop DA. In addition, one element of the five-element array
is a drop-wire suspended from a cable attached to the tops of two of the
four "real" towers. I have no clue as to how much tighter KPIG's night
pattern could be made, but for KGA to remain a Class A, KPIG would have to
continue limiting its night signal toward KGA. If KGA pulled in its night
pattern, the limitation on KPIG's nighttime signal to the north would be
relaxed because KGA's protected contour would lie much further north than it
does at present. In other words, the distance from KPIG to KGA's protected
contour might easily increase by a factor of three or four. That could allow
a substantial increase in KPIG's night power without modification of KPIG's
night pattern. If the minimum to the north could be made deeper, KPIG could
increase its power further. My guess is that with the appropriate mods at
KGA, KPIG might be able to increase its night power by a factor of 10 or
more without forcing KGA to give up its Class A status. It's not
inconceivable that KPIG could run as much as 5 kW at night without KGA
having to drop to a lower class.

--
Dan Strassberg, dan.strassberg@xxxxxxx
eFax 707-215-6367










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